KOSELUGO® (selumetinib) was the FIRST FDA-approved treatment proven to shrink NF1 PN in pediatric patients1,2*
*In SPRINT Phase 2 Stratum 1, 66% of pediatric patients achieved ≥20% PN volume reduction (33/50; 95% CI: 51, 79). DCO June 2018. These responses were confirmed at a subsequent assessment within 3 to 6 months.1
SPRINT Phase 2 Stratum 1 was an open-label, multicenter, single-arm study coordinated with the NCI. This study of 50 pediatric patients with NF1-related inoperable PN that caused substantial morbidity was designed to assess the efficacy and safety of Koselugo in reducing the volume of NF1 PN.1,3
The target PN was defined as the PN that caused relevant clinical symptoms or complications (PN-related morbidities). Response was confirmed by 3D MRI volumetric analysis at a subsequent assessment within 3 to 6 months.1,3
Pain intensity of the target PN was self-reported by patients ≥8 years of age using the NRS-11.3
See the Results
  • NF1 with symptomatic, inoperable PN (defined as PN that could not be completely surgically removed without risk of substantial morbidity due to PN location, invasiveness, or high vascularity)
  • At least 1 clinically significant PN-related morbidity
  • Evidence of MPNST, an optic glioma, malignant glioma, or other cancers requiring treatment with chemotherapy or radiation therapy
  • 42% (21/50) of patients had a progressive PN (growth ≥20% within 15 months prior to enrollment)
  • 30% (15/50) of patients had a non-progressive PN at baseline
  • Median target PN volume was 487 mL
(range: 5 mL to 3820 mL)
  • 24% (12/50) of patients had target PN in the neck and trunk
  • 24% (12/50) of patients had target PN in the trunk and limbs
  • Other patients had PN residing in the limbs, head, trunk only, or the head and neck
  • Patients had a median of 3 (range: 1 to 5) PN-related complications
  • The most common morbidities (≥20% of patients) were3: disfigurement (44/50; 88%), motor dysfunction (33/50; 66%), pain (26/50; 52%), airway dysfunction (16/50; 32%), visual impairment (10/50; 20%), and bladder/bowel dysfunction (10/50; 20%)
§Thirty-six patients had evaluable prestudy volumetric MRI data. 28% (14/50) of patients had insufficient data for PN progression status at baseline.3
Primary endpoint: ORR1¶#||
66% (33 out of 50) icon.
An independent centralized review of tumor response per REiNS criteria found an ORR of 44% (95% CI: 30, 59).1
ORR was defined as the percentage of patients with complete response (defined as disappearance of the target PN) or confirmed partial response (defined as ≥20% reduction in PN). Thirty-three partial responses were confirmed by 3D MRI volumetric analyses at a subsequent tumor assessment within 3 to 6 months. DCO June 2018.1
#The ORR assessment was conducted by a single NCI reviewer who was a SPRINT investigator and who evaluated all PN imaging from patients enrolled at all trial sites.1
||One more patient achieved ≥20% tumor shrinkage after 1.6 years.1,5
**Based on AstraZeneca analysis of NCI data (DCO June 2018).6
Timeline of onset of response among patients who responded to Koselugo in the SPRINT study as of DCO March 20215
††DOR was defined as the time from the pre-cycle volumetric MRI assessment of the first documented response (which was subsequently confirmed) until the pre-cycle volumetric MRI assessment of documented progression.5

‡‡95% CI: 41.2, NE.

§§A cycle was defined as 28 days.

¶¶At DCO June 2018, the median time to onset of response was 7.2 months (range: 3.3 months to 1.6 years).
##DCO February 2021. This information is from the SPRINT long-term follow-up study.7
Limitations of analysis
Limitations of the following exploratory patient-reported outcomes include small sample size, lack of a control group, and single-arm nature of the clinical trial. The patient-reported outcomes presented are secondary measures and, with the exception of the Pain Interference Index, have not been validated in NF1 PN.

Additionally, due to variability in tumor size, location, and relation to pain and other symptoms, statistical analyses failed to establish a direct correlation between tumor size reduction and patient-reported results.

Therefore, these findings should be interpreted with caution.
As reported in the SPRINT publication, 68% of patients reported some degree of improvement in at least one of the functional, patient-reported, and observer-reported outcome measures over 12 months of treatment3
Mean change from baseline in tumor pain intensity score at pre-cycle 13 as measured by the NRS-11 score in patients 8 to 18 years of age: −2.14 (95% CI: −3.14, −1.14).3||||***

After 12 months of treatment, a change of −≥2 points from baseline was observed in 74% (14/19) of patients 8 to 18 years of age with a baseline NRS-11 score of >0.3†††
A reduction in Pain Interference Index score from baseline was reported by 38% (11/29) of patients aged ≥8 years and 50% (21/42) of parents of pediatric patients aged ≥5 years at pre-cycle 13.3||||‡‡‡
||||For all scales, child-reported scores are for children 8 years of age or older and observer-reported scores are for children 5 years of age or older.3
***NRS-11 is a self-report that assesses the pain intensity of the physician-selected target tumor on an 11-point numeric scale over the past week.3,4
†††Physician-selected target tumor.3
‡‡‡The Pain Interference Index is a 6-item measure that assesses the degree to which pain has interfered with daily activities in the past week.3,4
View the long-term safety profile of Koselugo
Safety
Initial presentation
Stridor (noisy breathing)

History of URIs, likely secondary to airway deviation

Frequent need for oral steroids


Referred to hematologist/ oncologist by pediatrician because of:
Café-au-lait macules and axillary freckling, suggestive of NF1

Prominence on the right cheek and left neck, suggestive of NF1

Advanced Imaging showed:
PN extending from right mandible to the left brachial plexus/left upper extremity and left lung

MRI of an extensive inoperable PN before Koselugo. MRI showing shrinkage of the inoperable PN after 4 years of Koselugo.

Individual results may vary. Patient images courtesy of D Van Mater, MD.
Koselugo is indicated for patients 1 year of age and older with NF1 and symptomatic, inoperable PN, providing a treatment option for appropriate patients of nearly any age1
1 year icon. Continuous dosing icon. Support icon.
Download this patient brochure with practical information on starting Koselugo and the support team available
Download the Koselugo OneSource Patient Brochure
Patients taking Koselugo have access to a team of support specialists so they are never alone in their NF1 PN journey.

OneSource is Alexion’s free, personalized patient support program that ensures continuity of care and access to Koselugo from childhood to adulthood.
  • Navigating health insurance coverage
  • Ensuring continuous access to Koselugo
  • Providing personalized disease and treatment education
  • Hosting events to connect the NF1 PN community
  • Providing educational resources

Learn more about OneSource
Koselugo. Package Insert. AstraZeneca Pharmaceuticals LP. Koselugo (selumetinib) approved in US for paediatric patients with neurofibromatosis type 1 plexiform neurofibromas. AstraZeneca. April 13, 2020. Accessed December 2, 2025.
https://www.astrazeneca.com/media-centre/press-releases/2020/koselugo-selumetinib-approved-in-us-for-paediatric-patients-with-neurofibromatosis-type-1-plexiform-neurofibromas.html#
Gross AM, Wolters PL, Dombi E, et al. Selumetinib in children with inoperable plexiform neurofibromas. N Engl J Med. 2020;382(15):1430-1442. doi:10.1056/NEJMoa1912735 Gross AM, Wolters PL, Dombi E, et al. Selumetinib in children with inoperable plexiform neurofibromas. N Engl J Med. 2020;382(15):1430-1442 [Supplementary material: Protocol]. doi:10.1056/NEJMoa1912735 Data on File, REF-36656, AstraZeneca Pharmaceuticals LP. Data on File, REF-75729, AstraZeneca Pharmaceuticals LP. Gross AM, Dombi E, Wolters PL, et al. Long-term safety and efficacy of selumetinib in children with neurofibromatosis type 1 on a phase 1/2 trial for inoperable plexiform neurofibromas. Neuro Oncol. 2023;25(10):1883-1894. doi:10.1093/neuonc/noad086

IMPORTANT SAFETY INFORMATION
WARNINGS AND PRECAUTIONS
Left Ventricular Dysfunction. Koselugo can cause cardiomyopathy, defined as a decrease in left ventricular ejection fraction (LVEF) ≥10% below baseline. In the pediatric safety pool, Grade 2 LVEF decrease occurred, as well as decreased LVEF of ≥20% resulting in dose interruption and dose reduction. The median time to first occurrence of LVEF decrease was approximately 12 months. In the adult population, Grade 2 LVEF decrease occurred, with decreased LVEF resulting in dose interruption. The median time to first occurrence of LVEF decrease was approximately 4 months. Assess ejection fraction by echocardiogram prior to initiating treatment, every 3 months during the first year of treatment, every 6 months thereafter, and as clinically indicated. Withhold, reduce dose, or permanently discontinue Koselugo based on severity of adverse reaction. In patients who interrupt Koselugo for decreased LVEF, obtain an echocardiogram or a cardiac MRI every 3 to 6 weeks until resolution. Upon resolution of decreased LVEF, obtain an echocardiogram or a cardiac MRI every 2 to 3 months.

Ocular Toxicity. Koselugo can cause ocular toxicity, including retinal vein occlusion (RVO), retinal pigment epithelial detachment (RPED), and blurred vision. In the pediatric safety pool, blurred vision, photophobia, cataracts, ocular hypertension, and retinal tear occurred. Blurred vision resulted in dose interruption. RPED occurred in the pediatric population during treatment with Koselugo and resulted in permanent discontinuation. In the adult population, blurred vision and vitreous floaters occurred in patients receiving Koselugo. Conduct ophthalmic assessments prior to initiating Koselugo, at regular intervals during treatment, and for new or worsening visual changes. Permanently discontinue Koselugo in patients with RVO. Withhold Koselugo in patients with RPED, conduct ophthalmic assessments every 3 weeks until resolution, and resume Koselugo at a reduced dose.

Gastrointestinal Toxicity. Koselugo can cause gastrointestinal toxicities, including diarrhea and colitis. In the pediatric safety pool (N=134), diarrhea occurred in 59% of patients, in addition to diarrhea resulting in permanent discontinuation and dose interruption. In the adult population (N=71), diarrhea occurred in 42% of patients who received Koselugo, in addition to diarrhea resulting in dose interruption. The median time to first onset of diarrhea was approximately 2 months in the pediatric safety pool and 1 month in the adult population. Advise patients to start an anti-diarrheal agent (eg, loperamide) and to increase fluid intake immediately after the first episode of diarrhea. Withhold, reduce dose, or permanently discontinue Koselugo based on severity of adverse reaction.

Skin Toxicity. Koselugo can cause severe rashes, including dermatitis acneiform. In the pediatric safety pool (N=134), rash occurred in 68% of patients. The most frequent rashes included dermatitis acneiform (47%) and maculopapular rash (31%). Pruritus, alopecia, and eczema occurred. In the adult population (N=71), rash occurred in 85% of patients who received Koselugo. The most frequent rash included dermatitis acneiform (66%). Alopecia and pruritus occurred in patients who received Koselugo. Grade 3 rash and rash resulting in dose interruption and dose reduction occurred in both the pediatric safety pool and the adult population. Permanent discontinuation also occurred in the adult population. Monitor for severe skin rashes. Withhold, reduce dose, or permanently discontinue Koselugo based on severity of adverse reaction. 

Increased Creatine Phosphokinase (CPK). Koselugo can cause increased CPK, myalgia, and rhabdomyolysis. In the pediatric safety pool (N=134), increased CPK, based on laboratory data, occurred in 73% of patients, including Grade 3 or 4. In the adult population (N=71), increased CPK, based on laboratory data, occurred in 70% of patients who received Koselugo, including Grade 3 or 4. Increased CPK resulted in dose interruption and dose reduction in both the pediatric safety pool and adult population. Increased CPK concurrent with myalgia occurred in both populations, including one patient who permanently discontinued Koselugo for myalgia in the pediatric safety pool. Obtain serum CPK prior to initiating Koselugo, periodically during treatment, and as clinically indicated. If increased CPK occurs, evaluate for rhabdomyolysis or other causes. Withhold, reduce dose, or permanently discontinue Koselugo based on severity of adverse reaction.

Increased Levels of Vitamin E and Risk of Bleeding (Koselugo Capsules). Koselugo capsules contain vitamin E, which can inhibit platelet aggregation and antagonize vitamin K-dependent clotting factors. Supplemental vitamin E is not recommended if daily vitamin E intake (including the amount of vitamin E in Koselugo and supplement) will exceed the recommended or safe limits due to increased risk of bleeding. An increased risk of bleeding may occur in patients who are co-administered vitamin-K antagonists or anti-platelet antagonists with Koselugo capsules. Monitor for bleeding in these patients and increase international normalized ratio (INR) monitoring in patients taking a vitamin-K antagonist. Perform anticoagulant assessments more frequently and adjust the dose of vitamin-K antagonists or anti-platelet agents as appropriate. Koselugo oral granules do not contain vitamin E.

Embryo-Fetal Toxicity. Koselugo can cause fetal harm when administered during pregnancy. In animal studies, administration of selumetinib to mice during organogenesis caused reduced fetal weight, adverse structural defects, and effects on embryo-fetal survival at approximate exposures >5 times the human exposure at the clinical dose of 25 mg/m2 twice daily. Advise pregnant women of the potential risk to a fetus. Advise females of reproductive potential and males with female partners of reproductive potential to use effective contraception during treatment with Koselugo and for 1 week after the last dose.

ADVERSE REACTIONS
Common adverse reactions ≥40% in pediatric patients include vomiting, diarrhea, increased CPK, dry skin, paronychia, nausea, dermatitis acneiform, and pyrexia.
Common adverse reactions ≥40% in adult patients include rash (all), dermatitis acneiform, and diarrhea.

DRUG INTERACTIONS
Effect of Other Drugs on Koselugo
Concomitant use of Koselugo with a strong or moderate CYP3A4 inhibitor or fluconazole increased selumetinib plasma concentrations, which may increase the risk of adverse reactions. Avoid coadministration with Koselugo. If coadministration cannot be avoided, reduce Koselugo dosage.
Concomitant use of Koselugo with a strong or moderate CYP3A4 inducer decreased selumetinib plasma concentrations, which may reduce Koselugo efficacy. Avoid concomitant use with Koselugo.

SPECIAL POPULATIONS
Pregnancy & Lactation. Verify the pregnancy status of patients of reproductive potential prior to initiating Koselugo. Due to the potential for adverse reactions in a breastfed child, advise patients not to breastfeed during treatment with Koselugo and for 1 week after the last dose.

To report SUSPECTED ADVERSE REACTIONS, contact AstraZeneca at 1-800-236-9933 or at https://us-aereporting.astrazeneca.com or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

INDICATION
KOSELUGO is indicated for the treatment of adult and pediatric patients 1 year of age and older with neurofibromatosis type 1 (NF1) who have symptomatic, inoperable plexiform neurofibromas (PN).

Please see full Prescribing Information for Koselugo (selumetinib) at https://alexion.com/Documents/koselugo_uspi.pdf.

3D=3-dimensional; BSA=body surface area; CI=confidence interval; DCO=data cutoff; DOR=duration of response; FDA=Food and Drug Administration; MPNST=malignant peripheral nerve sheath tumor; MRI=magnetic resonance imaging; NCI=National Cancer Institute; NE=not evaluable; NF1=neurofibromatosis type 1; NRS-11=Numerical Rating Scale-11; ORR=overall response rate; PN=plexiform neurofibromas; REiNS=Response Evaluation in Neurofibromatosis and Schwannomatosis; URI=upper respiratory infection.